Abstract: An improved method of manufacturing galvanized steel tubing from steel strip having at least one galvanized surface, which surface becomes the exterior surface of the tubing is provided. In the method of the invention, after the steel strip is roll-formed and welded to complete the tubing and the welded seam is scarfed to remove irregularities, a quantity of an acid solution is applied to substantially only the scarfed area to react with oxidized metal, and the rinsed, leaving the non-scarfed galvanized exterior surface intact. The tubing is then heated to a temperature sufficient to cause the galvanized coating of the exterior surface to begin to flow and the tubing is regalvanized to produce an improved galvanized exterior surface, which is resistant to cracking along the scarfed area.

Abstract: An improved method of manufacturing galvanized steel tubing from steel strip having at least one galvanized surface, which surface becomes the exterior surface of the tubing is provided. In the method of the invention, after the steel strip is roll-formed and welded to complete the tubing and the welded seam is scarfed to remove irregularities, a quantity of an acid solution is applied to substantially only the scarfed area to react with oxidized metal, and then rinsed, leaving the non-scarfed galvanized exterior surface intact. The tubing is then heated to a temperature sufficient to cause the galvanized coating of the exterior surface to begin to flow and the tubing is regalvanized to produce an improved galvanized exterior surface, which is resistant to cracking along the scarfed area.

Abstract: A metallic wall having coined knockouts. The wall includes a first surface and a second surface spaced from the first surface. A plurality of spaced knockout portions are positioned in incipient apertures in the wall and are disposed substantially between the surfaces. Each knockout portion is defined by a first indentation encompassing the knockout portion and extending from the first surface, and by a second indentation encompassing the knockout portion and extending form the second surface. These indentations are in alignment with a web of material of substantially uniform thickness throughout its length spacing the indentations. The outside surface defining the first indentation is inclined inwardly. A coating is applied to the second surface after formation of the indentations. A sharp blow to the knockout portion from the second surface fractures the web to allow removal of the knockout portion without any material of the wall extending substantially beyond the first surface.